Assembly having a component enclosed by a housing, and device and method used in its manufacture

ABSTRACT

To provide an assembly which is as small as possible which contains a well-protected component and effectively dissipates heat, and to provide a device and a method for use in the rapid manufacture of such an assembly, an assembly includes a component and a housing from which the component is partially separated by narrow casting gaps filled with a casting compound containing a relatively large amount of filler. For the manufacture of such an assembly, a device is used for filling with casting compound and which includes a mounting for securing the assembly in a position which permits air to escape from the casting gaps, which have an external connection during filling. Also there are supply containers and supply lines for the casting compound which open into the casting gaps, and an apparatus for generating pressure. A method which is used to fill narrow casting gaps with casting compound by using such a device. The method involves introducing a casting compound of predetermined viscosity under pressure through the supply lines into the casting gaps, from which the air is displaced.

FIELD OF THE INVENTION

[0001] The present invention relates to an assembly which includes acomponent and a housing enclosing the component to which a region of thecomponent is attached, this region is separated from other regions ofthe component by a casting gap filled with a crosslinked castingcompound containing a filler, and to a device, and to a method which maybe performed using such a device, for filling casting gaps with acasting compound in the manufacture of such an assembly.

BACKGROUND INFORMATION

[0002] Such assemblies are conventional. The housing and the castingcompound protect the component from vibrations and moisture. Filling thecasting gap is not difficult, because it may be made sufficiently wideand a casting compound with a relatively low viscosity may be used. Withthe increasing trend toward miniaturization, however, the referencedconventional assemblies no longer completely meet the demands imposed onthem.

SUMMARY OF THE INVENTION

[0003] It is an object of the present invention to provide an assemblywhich takes up little space, which contains a component well-protectedfrom mechanical damage and moisture, and which is able to effectivelydissipate heat produced by the component, and to provide a device and amethod for use in the reproducible and rapid manufacture of such anassembly.

[0004] In the present invention, the feature “a component which isenclosed by a housing” also includes cases in which the housing enclosesmore than one component, and in these cases, casting gaps filled or tobe filled with casting compound also optionally include the gaps betweenthe components. In the description which follows, the term “assembly” isused even when the casting gaps between the housing and the componenthave not yet been filled with casting compound.

[0005] The narrow width of the casting gaps in the assembly according tothe present invention and the relatively high filler content in thecasting compound which induces good heat conductivity assure that heatfrom the component is effectively dissipated. The narrow widths of thecasting gaps also permit the assembly to be compactly configured. Bycombining the device according to the present invention and the methodaccording to the present invention, it is possible not only tosimultaneously satisfy the generally incompatible requirements that thecavity be narrow but it be filled with a casting compound containing arelatively large amount of filler, i.e., with a relatively viscouscasting compound, but also to fill the cavity without air inclusions,i.e., in a reproducible manner, as well as to perform this in a periodof time which is acceptable for industrial applications.

[0006] It may be advantageous if the filler content in the castingcompound relative to the total weight of the casting compound is betweenapproximately 20% and approximately 90% by weight, and even moreadvantageously, between approximately 50% and approximately 80% byweight, which corresponds to heat conductivities of the casting compoundbetween approximately 0.3 and approximately 2 watt/m° K and betweenapproximately 0.5 and approximately 1.3 watt/m° K, respectively.

[0007] It may be advantageous if the housing includes a tubular sleevewhich surrounds the component and a base to which the component and thesleeve are attached. In this regard, it may be advantageous for the baseto be inserted in one end of the tubular sleeve, the inserted end regionof the base including a cross section which is matched to the tubularcross section so that the end region fits closely against the interiorof the tube. It may be advantageous if the cured casting compound iselastic, due to the fact that a component which vibrates duringoperation, such as an actuator, e.g., a piezoelectric actuator, is thenable to advantageously vibrate through the casting compound and thehousing without damping. In this regard, it may be advantageous for thecomponent to have an oblong shape and for its longitudinal axis to beperpendicular to the base. For example, an oblong piezoelectric actuatorcontaining a plurality of layers perpendicular to the longitudinal axis,when energized, is able to create vibrations of higher amplitude than ashorter, thicker piezoelectric actuator manufactured from the sameamount of material.

[0008] It may be advantageous if the smallest dimension across thecasting gap between the sleeve surrounding the component and thecomponent itself is between approximately 0.05 mm and approximately 0.2mm, and the largest dimension is between approximately 1.4 mm andapproximately 2.6 mm.

[0009] To fill casting gaps with the casting compound, it may beadvantageous if at least one continuous borehole is introduced in theregion of the sleeve in which the base is inserted, and the insertedregion of the base provides for each borehole a transport path for afree-flowing medium between the surface region of the base facing towardthe inner wall of the cylinder and the end of the base facing toward theinterior of the tube, the transport paths running in such a manner that,as long as the sleeve is not firmly connected to the base, the sleeveand the base may be brought together in such a position that each of theat least one borehole opens into the transport path associated with it.

[0010] It may be advantageous if the casting compound contains resincomponents based on silicones, polyurethanes, and epoxide, and thefiller is selected from a material from the group including silicondioxide, aluminum oxide, titanium dioxide, boron nitride, aluminumnitride, and mixtures of these materials.

[0011] To fill the narrow casting gaps, the device according to thepresent invention may advantageously include at least one hollow needlefor supply, optionally placed on a nozzle, which is connected to atleast one supply container for the casting compound and which opens intothe assembly, and which includes a circular cross section and an innerdiameter between approximately 0.2 mm and approximately 2 mm.

[0012] In one example embodiment of the device, which for fillingcasting gaps may be advantageously insertable in the aforementionedassembly including a borehole in the sleeve, the at least one hollowneedle is positioned in such a manner that it may be inserted into atleast one continuous borehole in the housing of the attached assembly,the assembly is equipped so that a tubular sleeve and a base inserted inone end of the sleeve are included in the housing, that the at least oneborehole is situated in the region of the sleeve of the housing in whichthe base is inserted, and that the inserted end region of the baseprovides for each borehole a transport path for a free-flowing mediumbetween the surface region of the base facing toward the inner wall ofthe cylinder and the end of the base adjoining the casting gaps, and thesleeve and the base may be brought together in a position in which eachborehole is connected to the transport path associated with it, and thatthe end facing away from the base is open during filling. It may beadvantageous if the connection between the at least one borehole and thetransport path associated with it is interruptible by displacing thesleeve and the base with respect to one another.

[0013] In another example embodiment of the device, the at least onehollow needle is inserted into the assembly through an opening in thehousing and opens into a casting gap. It may be advantageous if the atleast one hollow needle is displaceable in the casting gap(s) in thedirection of filling and in the direction opposite to the direction offilling. During displacement it is favorable if guiding aids are presentto displace the at least one hollow needle in the casting gap(s) withoutcontacting the component and, when at least two hollow needles arepresent, to displace the hollow needles parallel to one another.

[0014] As an alternative to the hollow needles including a circularcross section, the hollow needles may also advantageously include across section which is adapted to the gap geometry perpendicular to thelongitudinal axis of the casting gaps. Thus, a larger area of thecasting gap cross section may be filled with the hollow needle crosssection than is possible using a hollow needle including a circularcross section.

[0015] In order to rapidly and uniformly deliver the casting compoundeven in narrow regions of the casting gap, it may be advantageous in themethod according to the present invention if the casting pressure isbetween approximately 0.5 bar and approximately 10 bar.

[0016] With regard to good dissipation of heat from the component, itmay be advantageous in the method according to the present invention ifa casting compound is used which has a viscosity between approximately1000 mPas and approximately 50,000 mPas. In the method according to thepresent invention, it may be advantageous if the casting compound isintroduced into the assembly via at least one hollow needle, and theviscosity of the casting compound determines the smallest inner crosssection of the hollow needle which is usable.

[0017] The present invention is described hereinafter in detail, withreference to the drawings which illustrate the example embodiments. Inthe following discussion the present invention is described, withreference to example embodiments of the assembly according to thepresent invention, of the method according to the present invention, andof the device according to the present invention. It is to beunderstood, however, that although the present invention may beexplained in an illustrative manner with reference to these exampleembodiments, various departures from the example embodiments areallowed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 shows in a perspective side view an example embodiment ofthe assembly according to the present invention, in which the componentis a piezoelectric actuator, and an example embodiment of the deviceaccording to the present invention for filling casting gaps in theassembly through boreholes in the assembly housing, using a castingcompound.

[0019]FIG. 2 shows, in a schematic perspective representation, detailsof the example embodiment of the assembly shown in FIG. 1.

[0020]FIG. 3 shows in a schematic representation a cross section throughthe piezoelectric actuator and the housing of the example embodiment ofthe assembly shown in FIGS. 1, 4, and 5.

[0021]FIG. 4 shows in a perspective side view a further exampleembodiment of the assembly according to the present invention in whichthe component is a piezoelectric actuator, and a partial detail of afurther example embodiment of the device according to the presentinvention for filling casting gaps in the assembly with a castingcompound using hollow needles which are introduced into the gap throughan opening in the housing.

[0022]FIG. 5 shows in a perspective side view the assembly shown in FIG.4, and a partial detail of yet a further example embodiment of thedevice according to the present invention which is similar to that shownin FIG. 4.

DETAILED DESCRIPTION

[0023]FIG. 1 shows an assembly 1, of which a sleeve 2 and a base 3projecting from the sleeve are seen. The sleeve and the base form thehousing for the component, which, as shown in FIG. 2, is a piezoelectricactuator 4 situated on base 3. The sleeve as well as the base are madeof metal. In FIG. 1, however, the sleeve is made of a transparentmaterial. It may be seen that the sleeve is filled with casting compound24. Sleeve 2 is cylindrical and includes a circular cross section. Oneend of the sleeve is closed by end region 5 of base 3 which is insertedinto the sleeve, at least the referenced end region is cylindrical andincluding a circular cross section and having an outer diameterapproximately equal to the inner diameter of the housing, and twogrooves 6 facing away from one another and running parallel to thelongitudinal axis are introduced in the cylindrical surface of insertedend region 5 and ending on the end surface facing toward the interior ofthe housing. The sleeve wall includes two boreholes 7, of which only oneis shown, which are positioned in such a manner that each borehole opensinto one of the respective grooves when the base is appropriatelypositioned with respect to the sleeve (filling position). Thepiezoelectric actuator is situated on the referenced end surface of thebase. The electrical lines by which the piezoelectric actuator receiveselectrical contact run in the grooves. The piezoelectric actuator formsa rectangular column. The longitudinal axis of the piezoelectricactuator coincides with the cylinder axes of the sleeve and the base.The diagonals through the cross section are somewhat (approximately 0.2mm) shorter than the inner diameter of the housing. Thus, as shown inFIG. 3, the sleeve and the piezoelectric actuator are separated from oneanother by narrow, oblong casting gaps 8 which envelop the piezoelectricactuator, the maximum distances between the sleeve and the piezoelectricactuator is between approximately 1 mm and approximately 2 mm, themaximum distance is approximately 1.5 mm. The four narrowings 9 betweenthe casting gaps are approximately 0.1 mm wide, i.e., approximately oneorder of magnitude smaller than the referenced maximum distances. Thepiezoelectric actuator has a maximum length such that its end facingaway from the base together with the other end of the sleeve lie in aplane perpendicular to the longitudinal or cylinder axes. In thefinished assembly, the other end of the sleeve is usually closed by acover.

[0024] In order to fill casting gaps 8 with the casting compound,assembly 1 is clamped in a mounting which is part of a device 10. Themounting includes a base plate 11, two threaded rods 12′, a tensioningbar 13, and nuts for the threaded rods. Base plate 11 includes anindentation into which the end of base 3 facing away from the housingmay be inserted. On the straight line through the midpoint of theindentation, running parallel to the plate surface, threaded rods 12′are situated which are symmetrically spaced in relation to the midpointof the indentation and perpendicular to the plate surface and which areanchored in the base plate. On each threaded rod are placed twoadjusting nuts 19, tensioning bar 13 including matching holes whosedistance from one another is equal to the distance between the threadedrods, and one wing nut 20′. The assembly which is inserted into theindentation may be clamped between the base plate and the tensioningbar, using the nuts, in such a manner that the longitudinal axis of theassembly is perpendicular to the plate, and, during filling, the openend of the assembly which forms the opening through which air may escapepoints upward. The casting compound is contained in two identical supplycontainers 15, included as part of the filling device, each of which isprovided with an outlet 17 and a connection for a pressure generator,such as a compressor. On each of the outlets a nozzle 16 is placed whichmerges into a hollow needle 18 having an inner diameter of approximately1.5 mm and which is inserted into one of boreholes 7 in the housing soas to fit closely against the hole wall. Alternatively, both nozzles maybe supplied from one supply container.

[0025] As casting compounds which are applicable to all the describedexample embodiments, silicone-based resins, polyurethanes, and epoxidesare used which are filled with at least one filler from the groupincluding silicon dioxide, aluminum oxide, titanium dioxide, boronnitride, and aluminum nitride to improve the heat conductivity of thecasting compound, the viscosity of the casting compound increasing withincreasing proportions of filler. Viscosities for which the flowabilityat an appropriate casting pressure is sufficient and the heatconductivity is satisfactory have values between approximately 1500 mPasand approximately 50,000 mPas, e.g., between approximately 2000 mPas andapproximately 30,000 mPas, which correspond—relative to the total weightof the casting compound—to filler contents between approximately 20% andapproximately 90% by weight and between approximately 50% andapproximately 80% by weight, respectively. For industrial applications,the minimum cross section of the hollow needle depends on the viscosity,within the described ranges, of the casting compound used in eachindividual case.

[0026] In order to fill casting gaps 8 in assembly 1, the castingcompound stored in supply containers 15 is pressed out, under pressure,from the hollow needles into grooves 6, and from there reaches thecasting gaps between the sleeve and the piezoelectric actuator andprogressively fills these, while displacing air, up to the upper edge ofthe sleeve. Due to the pressure applied (casting pressure), which isbetween approximately 0.5 bar and approximately 10 bar, and e.g., is≧approximately 3 bar, even casting compounds having medium andrelatively high viscosity are conveyed from the two oppositely situatedcasting gaps into which the grooves open, through narrowings 9 into thetwo other casting gaps, so that the surface area of the casting compoundin the casting gaps increases uniformly. Base 3 and sleeve 2 are thendisplaced sufficiently with respect to one another, i.e., rotated withrespect to one another about the common axis, so that boreholes 7 are nolonger situated opposite grooves 6, but instead are situated oppositeregions in the cylindrical surface of the base, with the result that thecasting compound filled inside is not able to flow back when hollowneedles 18 are pulled from boreholes 7. The casting compound filledinside is crosslinked, e.g., by adding heat. The base is firmlyconnected to the sleeve, e.g., by welding, and the end of the sleevefacing away from the base is usually closed tightly by a cover. This mayoccur before or after the crosslinking.

[0027] Alternatively, a hardener may be added to the casting compoundbefore it is used in filling (two-component system). An additionalsupply container or supply containers are provided for the hardener. Inthis case, both components are combined in a combination set connectedupstream from nozzles 17.

[0028] Assembly 21 shown in FIGS. 4 and 5 differs from assembly 1 shownin FIGS. 1 and 2 in that sleeve 22, unlike sleeve 2, includes noboreholes 7, and that the grooves introduced into base 25, optionallyfor the power supply, are not configured as a transport path for thecasting compound, unlike the case for base 3. In the assembly shown inFIGS. 4 and 5, which has not yet been filled with casting compound,piezoelectric actuator 4 is visible through sleeve 2.

[0029] Casting gaps 8 in assembly 21 are filled via two hollow needles18 which are inserted from the end of sleeve 22 facing away from thebase—which in this stage of the method is open —into the housing in sucha manner that the hollow needles open into two oppositely situatedcasting gaps. To perform filling, the assembly is clamped into device 30shown in FIG. 4 or in device 40 shown in FIG. 5.

[0030] Assembly 21 is clamped into a mounting in device 30. The mountingincludes base plate 11, two rods 12, tensioning bar 33, and nuts. Baseplate 11 includes an indentation into which the end of base 25 facingaway from the housing may be inserted. On the straight line through themidpoint of the indentation, running parallel to the plate surface, aresituated rods 12 which are symmetrically spaced in relation to themidpoint of the indentation and perpendicular to the plate surface andwhich are anchored in the base plate. On their ends facing away from thebase plate, rods 12 include a thread having a diameter which is smallerthan the diameter of the lower portion of rods 12. Tensioning bar 33,together with holes which fit the thread and whose midpoints areseparated by a distance which is equal to the distance between themidpoints of rods 12, and knurled nut 20 are placed on each of the rods.The assembly which is inserted into the indentation may be clampedbetween the base plate and the tensioning bar using the nuts, e.g., byplacing a pressure spring 14 between the upper end of the sleeve and thetensioning bar, in such a manner that the longitudinal axis of theassembly is perpendicular to the base plate, and its end, which is openduring filling, points upward. Above the tensioning bar, but not firmlyconnected to it, a nozzle holder 23 is arranged which is penetrated by anozzle-like reducing fitting 26. The reducing fitting is situated withits upper end at the discharge of a supply container 15, oralternatively is connected to a mixer, provided that the resin componentof the casting compound forms a two-component system (see above). Thesupply container(s) is (are) each provided with a pressure generator,such as a compressor. The reducing fitting is connected at its lower endto a distributor inside the nozzle holder. The distributor includes twooutlets, on each of which is situated a nozzle. Hollow needles 18 areplaced on each of the nozzles, and project downward from the nozzleholder and are aligned with guide sleeves which run parallel to oneanother and which are integrated into the tensioning bar as guide aidsfor the hollow needles. To enable the hollow needles to align with theguide sleeves, the distance between the midpoints of the nozzles andthus of the hollow needles is the same as the distance between themidpoints of the guide sleeves, and the hollow needles run parallel tothe longitudinal axes of the guide sleeves. The guide sleeves arepositioned with relation to the clamped assembly in such a manner thattheir longitudinal axis runs parallel to the cylinder axis of sleeve 22,and that the hollow needles led into the guide sleeves may be held intwo oppositely situated casting gaps 8 in assembly 21, where thedistance between the sleeve and the piezoelectric actuator is greatest(approximately 1.5 mm) approximately midway between sleeve 22 andpiezoelectric actuator 4, without contacting the piezoelectric actuator.The hollow needles may include a circular cross section. Alternatively,the cross section of the hollow needles may be adapted to the crosssection of the casting gaps, such as a sector of a circle or perhapsonly an ellipse, for example, so that the cross sections are thenappropriately aligned with one another. The nozzle holder is attached toa lifting device by which the nozzle holder together with the supplycontainer may be moved vertically, either manually or by sensor controland motor drive.

[0031] The above description regarding the filling of the casting gapsin assembly 1 applies to the casting compound which is to be filled intothe casting gaps of assembly 21.

[0032] To fill the casting gaps in assembly 21 with casting compoundusing mounting 30, first the nozzle holder is lowered so that the hollowneedles of appropriate length are inserted far enough into the castinggaps that the ends of the hollow needles are situated just above base25. As casting compound flows in, the ends of the needles are graduallypulled out as the level of casting compound rises, so that the hollowneedles are never submerged, but instead end just above the surface ofthe casting compound being filled inside. The casting compound is underpressure (casting pressure) as it leaves the hollow needle. Supported bythis pressure, the casting compound—even when it has a relatively highviscosity—flows completely over narrowings 9 between the sleeve and thepiezoelectric actuator and also flows into the casting gaps into whichhollow needles are not inserted, with the result that the surface levelof the casting compound rises uniformly in the entire cavity. Withdrawalof the hollow needles and lifting of the nozzle holder may beaccomplished manually, corresponding to the visually observed level,or—as preferred for industrial manufacturing—using a sensor—controlledmotor drive. The filling operation is complete when the casting gapshave been filled up to the open end of the housing. Also, the base andsleeve of assembly 21 may be firmly connected to one another before thefilling operation.

[0033] After the casting gaps are filled, the casting compound iscrosslinked by heating, and the end of the sleeve facing away from thebase is tightly closed by a cover.

[0034] Device 40 shown in FIG. 5 may also be used in filling of assembly21. The hollow needles which open into the casting gaps do not dip intothe casting gaps, as described above, but instead their ends are fixedat the upper end of the casting gaps, and during filling, the hollowneedles are not lifted corresponding to the filling rate. As a result,device 40 differs from mounting 30 by the fact that two adjusting nuts19 are present on the thread at the end of each rod 12 underneathtensioning bar 33 which allow the distance between the base plate andthe tensioning bar to vary, and by the fact that nozzle holder 23 isconnected to the tensioning bar and there is no lifting device for thenozzle holder, and by the fact that, over the adjustable distancesbetween the base plate and the tensioning bar, the hollow needles areonly long enough so that the needle ends may be fixed at the upper endof the casting gaps. The hollow needles are thus aligned with thecasting gaps in the same manner as described above in conjunction withdevice 30.

[0035] After assembly 21, as it has been described with reference toFIG. 4, has been clamped into device 40, in order to fill the castinggaps with casting compound, the needle ends which are at the same heightas the upper end of the piezoelectric actuator are positioned by usingadjusting nuts 19 to correspondingly lower or raise the tensioning bar.Filling is then performed in such a manner that casting compound isallowed to flow into the casting gaps until the level is approximatelythe same height as the needle ends. In this case, there is no use inhaving the casting compound flow into the casting gaps under pressure.Moreover, in this alternative the casting compound may only be conveyedthrough the narrowings between the casting gaps when the viscosity ofthe casting compound is relatively low, i.e., ≦approximately 1500 mPas.

[0036] The present invention is described in more detail hereinafterwith reference to two examples.

EXAMPLE 1

[0037] Assembly 1 was clamped into the mounting included in device 10.The casting compound was filled at a pressure of ≧6 bar throughboreholes 7 in the housing and through grooves 6 into the casting gapsbetween the housing and the piezoelectric actuator. The casting compoundwas a silicone resin filled with aluminum oxide, having a viscosity of30,000 mPas. The aluminum oxide content relative to the total weight ofthe casting compound was approximately 70% by weight. The approximately1.5 g of casting compound required for complete filling was introducedwithin ≦3 seconds. The sleeve and the base were then rotated withrespect to one another to interrupt the connection between the boreholesand the casting gaps. The crosslinked casting compound had a heatconductivity of 1.2 watt/m° K.

EXAMPLE 2

[0038] Assembly 21 was clamped into the mounting included in device 30.The casting compound was pressed at a pressure of ≧6 bar into thecasting gaps between the housing and the piezoelectric actuator, usinghollow needles, and the hollow needles were pulled upward as the fillingprogressed. The casting compound was a silicone resin filled withquartz, having a viscosity of 2000 mPas. The quartz content relative tothe total weight of the casting compound was approximately 60% byweight. The approximately 1.5 g of casting compound required forcomplete filling was introduced within ≦3 seconds. The cured compoundhad a heat conductivity of 0.8 watt/m° K

What is claimed is:
 1. An assembly, comprising: a component; and ahousing enclosing the component, a region of the component beingattached to the housing and the attached region being separated fromother regions of the component by a plurality of casting gaps filledwith a crosslinked casting compound containing a filler; whereindistances across the plurality of casting gaps between the housing andthe component are small, and the crosslinked casting compound includes arelatively high filler content.
 2. The assembly according to claim 1,wherein: the distances across the plurality of casting gaps and thefiller content of the crosslinked casting compound are adjusted to oneanother with regard to a predetermined heat dissipation.
 3. The assemblyaccording to claim 1, wherein: the distances across the plurality ofcasting gaps are approximately ≦3 mm.
 4. The assembly according to claim1, wherein: the filler content relative to a total weight of thecrosslinked casting compound is between 20% and 90% by weight.
 5. Theassembly according to claim 4, wherein: the filler content is between50% and 80% by weight.
 6. The assembly according to claim 1, wherein:the housing is made of a metal.
 7. The assembly according to claim 1,wherein: the housing includes a base and a tubular sleeve that surroundsthe component, the base being attached to the component and the tubularsleeve.
 8. The assembly according to claim 7, wherein: the base isplaced in an end of the tubular sleeve, an inserted end region of thebase including a cross section which is matched to a tubular crosssection so that the inserted end region fits closely against an interiorof the tubular sleeve.
 9. The assembly according to claim 8, wherein:the component is attached to an end of the inserted end region thatfaces toward the interior of the tubular sleeve.
 10. The assemblyaccording to claim 8, wherein: the tubular sleeve is a hollow cylinder,and at least the inserted end region of the base is a cylinder block.11. The assembly according to claim 10, wherein: each of the hollowcylinder and the cylinder block includes a circular cross section. 12.The assembly according to claim 1, wherein: the crosslinked castingcompound is elastic.
 13. The assembly according to claim 12, wherein:the component is an actuator.
 14. The assembly according to claim 13,wherein: the actuator is a piezoelectric actuator.
 15. The assemblyaccording to claim 10, wherein: the component has an oblong shape. 16.The assembly according to claim 15, wherein: a longitudinal axis of thecomponent extends parallel to at least one axis of the hollow cylinderand the cylinder block.
 17. The assembly according to claim 16, wherein:the longitudinal axis coincides with the at least one axis of the hollowcylinder and the cylinder block.
 18. The assembly according to claim 15,wherein: the component is a cuboid.
 19. The assembly according to claim18, wherein: the cuboid is a rectangular column.
 20. The assemblyaccording to claim 7, wherein: a smallest dimension across the pluralityof casting gaps between the tubular sleeve and the component is between0.05 mm and 0.2 mm, and a largest dimension is between 1.4 mm and 2.6mm.
 21. The assembly according to claim 20, wherein: the smallestdimension is 0.1 mm and the largest dimension is 1.5 mm.
 22. Theassembly according to claim 8, wherein: at least one continuous boreholeis included in the end of the tubular sleeve in which the base isplaced, the inserted end region of the base provides for the at leastone continuous borehole a transport path for a free-flowing mediumbetween a surface region of the base facing toward an inner wall of thetubular sleeve and an end of the base facing toward the interior of thetubular sleeve, and the tubular sleeve and the base are brought togetherin a position such that the at least one continuous borehole isconnected to the transport path associated therewith.
 23. The assemblyaccording to claim 22, wherein: the transport path is formed by a grooveintroduced into the surface region facing toward the inner wall of thetubular sleeve, the groove beginning where the at least one continuousborehole meets the base, extending parallel to an axis of the tubularsleeve and opening into a space between the component and the tubularsleeve.
 24. The assembly according to claim 1, wherein: the crosslinkedcasting compound includes at least one resin based on a silicone, apolyurethane, and an epoxide.
 25. The assembly according to claim 1,wherein: the filler includes one of a silicon dioxide, an aluminumoxide, a titanium dioxide, a boron nitride, an aluminum nitride, and amixture including at least two of the silicon dioxide, the aluminumoxide, the titanium dioxide, the boron nitride, and the aluminumnitride.
 26. The assembly according to claim 7, wherein: the tubularsleeve is firmly connected to the base.
 27. The assembly according toclaim 7, further comprising: a cover for covering an end of the tubularsleeve facing away from the base.
 28. A device for filling casting gapsduring manufacture of an assembly, comprising: a mounting to securelyhold the assembly in a position that, while the casting gaps are filledwith a crosslinkable casting compound that contains a filler, permitsair to escape from the casting gaps, in dependence upon a filling rate,through an opening in an assembly housing during filling; at least onesupply line, for the crosslinkable casting compound, that opens into thecasting gaps; at least one supply container for the crosslinkablecasting compound; and an arrangement for exerting pressure on thecrosslinkable casting compound such that the crosslinkable castingcompound passes through the at least one supply line.
 29. The deviceaccording to claim 28, wherein: the mounting is formed from a baseplate, a tensioning bar, and at least one component to fix thetensioning bar in a predetermined location and position with respect tothe base plate.
 30. The device according to claim 28, wherein: thearrangement includes at least one compressor.
 31. The device accordingto claim 28, further comprising: a nozzle; and at least one hollowneedle, for supply, the nozzle being connected to the at least onesupply container for the crosslinkable casting compound and opening intothe assembly.
 32. The device according to claim 31, wherein: the atleast one hollow needle includes a circular cross section.
 33. Thedevice according to claim 32, wherein: the at least one hollow needlehas an inner diameter between 0.2 and 2 mm.
 34. The device according toclaim 31, wherein: the at least one hollow needle is insertable into atleast one continuous borehole in the assembly housing; the assembly isequipped such that a tubular sleeve and a base inserted in an end of thetubular sleeve are included in the assembly housing; the at least onecontinuous borehole is arranged in a region of the tubular sleeve of theassembly housing in which the base is inserted; an inserted end regionof the base provides for the at least one continuous borehole atransport path for a freeflowing medium between a surface region of thebase facing toward an inner wall of the tubular sleeve and an end of thebase adjoining the casting gaps; the tubular sleeve and the base arebrought together into a position such that a connection is formedbetween the at least one continuous borehole to the transport pathassociated therewith; and an end of the tubular sleeve facing away fromthe base is open during filling.
 35. The device according to claim 34,wherein: the connection between the at least one continuous borehole andthe transport path associated therewith is interruptible by displacingthe tubular sleeve and the base with respect to one another.
 36. Thedevice according to claim 31, wherein: the at least one hollow needle isguided into the assembly through the opening in the assembly housing andopens into one of the casting gaps.
 37. The device according to claim36, wherein: the assembly housing includes a tubular sleeve and a baseinserted in an end of the tubular sleeve, a second end of the tubularsleeve being open during filling.
 38. The device according to claim 36,further comprising: at least another hollow needle for filling; abranching between a discharge from the at least one supply container andthe at least one hollow needle and the at least another hollow needle,the branching including an outlet for each of the at least one hollowneedle and the at least another hollow needle, each outlet ending in arespective other nozzle on each of which one of the at least one hollowneedle and the at least another hollow needle is placed.
 39. The deviceaccording to claim 36, wherein: the at least one hollow needle isfixable at least one end of the casting gaps facing toward the opening.40. The device according to claim 38, wherein: the at least one hollowneedle is displaceable, together with the branching and the nozzle at anending of the outlet, in the casting gaps in a direction of filling andin a direction opposite to the direction of filling.
 41. The deviceaccording to claim 40, wherein: the at least one hollow needle ismanually displaceable.
 42. The device according to claim 40, wherein:the at least one hollow needle is sensor-controlled and motor-driven.43. The device according to claim 40, further comprising: a plurality ofguide aids to displace the at least one hollow needle in the castinggaps without contacting a component and, when the at least anotherhollow needle is present, to displace the at least one hollow needle andthe at least another hollow needle parallel to one another.
 44. Thedevice according to claim 43, wherein: the plurality of guide aidsincludes a plurality of guide sleeves which are integrated into atensioning bar.
 45. The device according to claim 38, wherein: the atleast one hollow needle and the at least another hollow needle include anon-circular cross section which is adapted to a gap geometryperpendicular to a longitudinal axis of the casting gaps.
 46. The deviceaccording to claim 45, wherein: the non-circular cross section is anellipsoid.
 47. A method for filling casting gaps using a device inmanufacture of an assembly, comprising: introducing a crosslinkablecasting compound under pressure through at least one supply line intothe casting gaps, the crosslinkable casting compound containing a fillerand having a predetermined viscosity; and displacing an escaping airfrom the casting gaps through an opening in a housing of the assembly.48. The method according to claim 47, further comprising the step of:determining a minimum pressure under which the crosslinkable castingcompound leaves an opening of the at least one supply line as a functionof the predetermined viscosity, at least one dimension of at least onenarrowest location in the casting gaps, and a targeted filling speed.49. The method according to claim 48, wherein: filling is performed at acasting pressure between 0.5 bar and 10 bar.
 50. The method according toclaim 49, wherein: filling is performed at a casting pressure ≧3 bar.51. The method according to claim 47, wherein: the predeterminedviscosity of the crosslinkable casting compound is between 1000 mPas and50,000 mPas.
 52. The method according to claim 51, wherein: thepredetermined viscosity is between 1500 mPas and 35,000 mPas.
 53. Themethod according to claim 47, wherein: the predetermined viscosity ofthe crosslinkable casting compound is adjusted via a filler content ofthe crosslinkable casting compound.
 54. The method according to claim47, wherein: the crosslinkable casting compound is introduced via atleast one hollow needle, the predetermined viscosity of thecrosslinkable casting compound determining a smallest inner diameter ofthe at least one hollow needle which is usable.
 55. The method accordingto claim 54, wherein: the predetermined viscosity of the crosslinkablecasting compound is 2000 mPas and the at least one hollow needleincludes a circular cross section, an inner diameter of the at least onehollow needle being ≧0.3 mm.
 56. The method according to claim 54,wherein: the predetermined viscosity of the crosslinkable castingcompound is 30,000 mPas and the at least one hollow needle includes acircular cross section, an inner diameter of the at least one hollowneedle being ≧1.0 mm.
 57. The method according to claim 47, wherein: thehousing of the assembly includes a tubular sleeve and a base, the basebeing inserted in a first end of the tubular sleeve; at least onecontinuous borehole is arranged in a region of the tubular sleeve of thehousing in which the base is inserted; an inserted end region of thebase provides for the at least one continuous borehole a transport pathfor a free-flowing medium between a surface region of the base facingtoward an inner wall of the tubular sleeve and an end of the baseadjoining the casting gaps; a second end of the tubular sleeve facesaway from the base and is open during filling; the crosslinkable castingcompound is introduced through at least one hollow needle after the atleast one hollow needle has been inserted into the at least continuousborehole; and the tubular sleeve and the base are brought together in aposition to form a connection between the at least one continuousborehole and the transport path associated therewith.
 58. The methodaccording to claim 57, wherein: after filling, the connection betweenthe at least one continuous borehole and the transport path isinterrupted by moving the tubular sleeve and the base with respect toone another.
 59. The method according to claim 47, wherein: at least onehollow needle is inserted into the assembly through the opening in thehousing in such a manner that the at least one hollow needle opens intoone of the casting gaps.
 60. The method according to claim 59, wherein:the housing includes a tubular sleeve and a base inserted in a first endof the tubular sleeve, a second end of the tubular sleeve being openduring filling.
 61. The method according to claim 59, wherein: the atleast one hollow needle is fixed on an end of at least one of thecasting gaps which faces toward the at least one hollow needle duringinsertion, and the casting gaps are then filled with the crosslinkablecasting compound.
 62. The method according to claim 59, wherein: the atleast one hollow needle is inserted into at least one of the castinggaps; and filling is then performed using the crosslinkable castingcompound, the at least one hollow needle being withdrawn correspondingto a progress of filling.
 63. The method according to claim 47, wherein:the crosslinkable casting compound includes a resin which contains afiller and which is based on a silicone, a polyurethane, and an epoxidein a form of one of a one-component system and a two-component system.64. The method according to claim 63, wherein: the at least one fillerincludes one of a silicon dioxide, an aluminum oxide, a titaniumdioxide, a boron nitride, an aluminum nitride, and a mixture includingat least two of the silicon dioxide, the aluminum oxide, the titaniumdioxide, the boron nitride, and the aluminum nitride.
 65. The methodaccording to claim 47, wherein: the crosslinkable casting compound iscrosslinked after filling.